Cope.] ^^ [May 7, 



tilian in their single occipital condyle, ossification of the basicranial carti- 

 lage, and single vomer. 



Thus the reptiles and batrachia of the Permian period resembled each 

 other and the Mammalia, more closely than do the corresponding existing 

 forms. 



PELYCOSAURIA. 

 THEROPLEURA Cope. 



Paleontological Bulletin No. 29, May, 1878, p. 519, Proceed. Amer. 

 Philos. Soc, 1878, p. 519. 



A more complete specimen of the Theropleura tmiformis than any 

 hitherto obtained gives the following generic characters. 



The teeth are generally similar to those of Glepsydrops and Dimetrodon, 

 having compressed crowns with fore and aft cutting edges. The incisors 

 are distinguished by the presence of a diastema. Posteriorly to this the 

 teeth increase in size, and then diminish ; one tooth near the middle of the 

 series is the largest, but does not in this species very much exceed the 

 others. There is at least one large incisor tooth. The bones of the head 

 are smooth, and not sculptured ; a character distinguishing the genus from 

 Ectocynodon. The symphysis of the mandible is short. 



The neural arches of the vertebrae are all distinct from the centra. In- 

 tercentra are not present in any of the thirteen vertebrae preserved, but 

 there was probably one below the centrum of the atlas. The ribs are two- 

 headed, the capitular process extending downward to the anterior border 

 of the centrum. The neural spines of some of the vertebrae are greatly 

 elevated as in the species of Glepsydrops and Dimetrodon. The scapula is 

 long ; the ilium is similar to that of the genera named. A character 

 which has not been detected in either of the genera named is the presence 

 of dermal rods, which from their position adherent to the vertebrae, I sus- 

 pect to be abdominal, and similar to those of the genus O'estocejyhahis. 

 This is a batrachian character. The neural spine of the axis is extended 

 fore and aft. The odontoid is distinct and is of large size. It has lateral 

 and inferior articular surfaces. 



Theeopleura itniformis Cops. 



Paleontological Bulletin No. 29, p. 519, 1878. 



This species is about the size of one of the larger Varanidt^, and about 

 equal to the Glejysydrops natalis. It is characterized by a long and acuminate 

 head, with a large lateral nostril on each side, well forwards, and approach- 

 ing near the border of the diastema. In the specimen the top of the head 

 is crushed and the postorbital portion is wanting. Anterior to the large 

 lateral tooth there are nine teeth ; posterior to it there are eighteen. The 

 anterior cutting edge of the crown does not extend so near the base as the 

 posterior, and is best marked on the anterior teeth. In the crowns pre- 

 served the edges are not serrate. 



